Field of the Invention
This invention relates to an electroconductive resin paste. More particularly it relates to an electroconductive resin paste suitable for bonding a semiconductor element onto a supporting member therefor and a semiconductor device using the same.
Description of the Related Art
As a process for bonding a semiconductor element to a substrate therefor such as lead frame, etc., (1) Au-Si eutectic process, (2) soldering process, (3) resin paste process, etc. have so for been known. However, the process (1) has drawbacks that use of gold results in a high cost and also a processing temperature is as high as about 400.degree. C. The process (2) is cheaper than the process (1), but has drawbacks that it is necessary to provide a thin coating of gold on the back surface of the semiconductor element, so that a cost is required for forming the thin coating. The process (3) uses a resin paste obtained by having silver powder as a filler, blended with a base resin such as an epoxy resin or a polyimide resin; hence the process has advantages that it is cheaper than the processes (1) and (2), and that it can be employed at a temperature of 200.degree. C. or lower. Thus, at present, this resin paste process has been prevailing.
However, since conventional resin paste is required to be cured by heating in an oven at 150.degree. C. to 200.degree. C. for one to two hours, there has been a drawback that rationalization by making the semiconductor assembly steps in-line is difficult. Further, in the case where cure is effected within one minute, there have been problems that the shell stability life is short, the adhesion strength, particularly the hot adhesion strength at the time of heating the resins to 200.degree. C. to 350.degree. C. is low and a large number of voids occurs.